Numerous systems for monitoring analyte (e.g., glucose) amount or concentration in a subject are known in the art, including, but not limited to the following: U.S. Pat. Nos. 5,362,307, 5,279,543, 5,695,623; 5,713,353; 5,730,714; 5,791,344; 5,840,020; 5,995,860; 6,026,314; 6,044,285; 6,113,537; 6,188,648, 6,326,160, 6,309,351, 6,299,578, 6,298,254, 6,284,126, 6,272,364, 6,233,471, 6,201,979, 6,180,416, 6,144,869, 6,141,573, 6,139,718, 6,023,629, 5,989,409, 5,954,685, 5,827,183, 5,771,890, and 5,735,273.
Self monitoring of blood glucose (BG) is a critical part of managing diabetes. However, most procedures for obtaining such information are invasive, painful and provide only periodic measurements. Results from the Diabetes Control and Complication Trial Research Group, (The Diabetes Control and Complication Trial Research Group. N Engl J Med. 1993;329:997–1036), UK Prospective Diabetes Study (UK Prospective Diabetes Study (UKPDS) Group. Lancet. 1998;352:837–853), and Kumamoto trials (Ohkubo Y, Kishikawa H, Araki E, et al. Diabetes Res Clin Pract. 1995;28:103–117) showed that a tight glucose control regiment, which uses frequent glucose measurements to guide the administration of insulin or oral hypoglycemic agents, leads to a substantial decrease in the long-term complications of diabetes; however, there was a 3-fold increase in hypoglycemic events (The Diabetes Control and Complication Trial Research Group. N Engl J Med. 1993;329:997–1036.). Moreover, as many as 7 BG measurements per day were not sufficient to detect a number of severe hypoglycemic and hypoglycemic events (Ohkubo Y, Kishikawa H, Araki E, et al. Diabetes Res Clin Pract. 1995;28:103–117.).
The GlucoWatch® (Cygnus, Inc., Redwood City, Calif.) biographer provides a means to obtain painless, automatic, frequent and noninvasive glucose measurements (see, for example, U.S. Pat. Nos. 6,326,160, 6,309,351, 6,299,578, 6,298,254, 6,284,126, 6,272,364, 6,233,471, 6,201,979, 6,180,416, 6,144,869, 6,141,573, 6,139,718, 6,023,629, 5,989,409, 5,954,685, 5,827,183, 5,771,890, and 5,735,273). The device provides up to 3 readings per hour for as long as 12 hours after a single BG measurement for calibration (Tamada, et al., JAMA 282:1839–1844, 1999).
Such a monitoring system, which gives automatic and frequent measurement, supplies detailed information on glucose patterns and trends that might identify opportunities for improved BG control. Automatic readings also provide the opportunity for an alarm to be sounded in response to values below a user-selected alert level or as a result of rapid declines in the measured glucose values. Such alarms provide a method to reduce the risks of hypoglycemia and make intensive therapy for persons with diabetes safer and acceptable to more patients.
Further, such monitoring systems can be used to measure an amount or concentration, in a subject, of one or more analytes, where the one or more analytes may be in addition to or other than glucose (see, e.g., WO 96/00109, published 4, Jan. 1996.
The present invention offers methods of improving performance of analyte monitoring systems that supply a series of analyte-related signals over time, for example, the GlucoWatch biographer.